Expanding her horizons in research at Princeton

By Steven Schultz

Princeton NJ -- When Catriona Chambers finishes her senior thesis in electrical engineering she will be ready to graduate -- but not from Princeton. She is an exchange student from Oxford University, which also requires students to complete an independent project during their final year.

Catriona Chambers

Oxford officials can rest assured that Chambers is meeting that requirement, said Sigurd Wagner, who is serving as her adviser. Chambers is working at the cutting edge of electronics and materials research, developing micro-scale stretchable cables that could be used in "electronic skins" -- supple sheets of electronics for touch-sensitive prosthetics or other devices. On April 25, she will present the results of her work at an international meeting of materials scientists in San Francisco.

"She is completely reliable, not just carrying out instructions, but doing everything that is necessary to make an experiment work," said Wagner, a professor of electrical engineering. "And she comes back with armloads of data.

"She does graduate student work, I must say," Wagner added. "I am very happy to have her."

For Chambers, the experience is her first foray into anything other than the prescribed regimen of engineering courses she has taken at Oxford. "The whole thing is really quite new to me," she said of the independent work. "Our work at Oxford is quite theoretical, not so practical."

The experience has prompted her to give serious consideration to graduate school, which is something "I never would have thought of before," she said. "I just really like Professor Wagner's group. It's really been great."

Her project involves depositing microscopically thin layers of chromium and gold onto strips of rubber. She built a device that automatically stretches the samples in small increments and measures how far and how many times they can stretch and still conduct electricity. She uses an electron microscope and other state-of-the-art tools to take pictures of the samples and analyze their structures and failures.

Other members of Wagner's group, including postdoctoral researcher Stéphanie Périchon-Lacour and graduate student Joyelle Jones, laid the groundwork for the project and are experimenting with different techniques for making the flexible connectors. Over the last few months, the group's approach has yielded dramatic results: The rubber-backed metal can be stretched by 30 percent without breaking.

"It is a surprise to us," said Zhigang Suo, a professor of mechanical and aerospace engineering and a leading theoretician on the physical properties of thin-film metals. "If you try it with aluminum foil at home, you find you can't stretch it. People have tried many metals over many years, and they only stretch 1 or 2 percent."

Chambers said she has particularly enjoyed being part of the interplay between the experimentalists in the electrical engineering group and Suo's theoretical group in mechanical engineering. "They bounce ideas off each other," she said. "We'll see some sort of phenomenon and we'll pass it along to the mechanical department to see what they think." She is now taking a graduate-level class in materials and mechanics from Suo.

The chance to look beyond a narrow discipline has been an important part of Chambers' experience as an exchange student. At Oxford, most students do not take any classes outside their chosen discipline, she said. At Princeton, Chambers has taken two semesters of economics in addition to a variety of engineering classes.

"I really enjoyed my time at Oxford, and I am really enjoying my time here," she said, "but I find they are so different in every way. I just can't even begin to compare them."

Chambers is one of two Oxford engineering students who are studying at Princeton for the first year of a newly established exchange program between the two institutions. She said she plans to attend Princeton's graduation, but will return to Oxford later in June to receive her degree.

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Editor: Ruth StevensCalendar editor: Carolyn GellerStaff writers: Jennifer Greenstein Altmann, Steven SchultzContributing writers: Karin Dienst, Eric Quinones, Cynthia YoderPhotographer: Denise ApplewhiteDesign: Mahlon Lovett, Laurel Masten Cantor, Margaret WestergaardWeb edition: Mahlon Lovett